Blowby-gas reflux system, blowby-gas reflux-system control device, and recording medium

ABSTRACT

A blowby-gas reflux system 60 has: a blowby-gas reflux path 70; an atmospheric release mechanism 90 that releases, into the atmosphere, blowby gas Gb that has passed through an oil separator 80; and a control device 50. The control device 50 is provided with: a determination unit 51 that determines whether oil caulking occurs in a compressor 41 on the basis of the operating state of the compressor; and a control unit 51 that stops the release of the blowby gas into the atmosphere performed by the atmospheric release mechanism if the determination unit determines that oil caulking does not occur, and that causes the atmospheric release mechanism to release the blowby gas into the atmosphere if the determination unit determines that oil caulking occurs.

TECHNICAL FIELD

The present disclosure relates to a blow-by gas reflux system, a blow-by gas reflux system control device and a storage medium.

BACKGROUND ART

In the related art, known is a blow-by gas reflux system including a blow-by gas reflux path for refluxing a blow-by gas discharged from an internal combustion engine to an intake passage on a further upstream-side than a compressor of a supercharger after causing the blow-by gas to pass through an oil separator configured to remove oil from the blow-by gas (for example, refer to PTL 1). According to the blow-by gas reflux system, it is possible to suppress oil contained in the blow-by gas discharged from the internal combustion engine from being released into the atmosphere in a large amount.

In the meantime, PTL 2 can be exemplified as another patent literature. PTL 2 discloses a phenomenon where oil contained in the blow-by gas caulks (carbonization) (referred to as “oil caulking”).

CITATION LIST Patent Literature

PTL 1: JP-A-2011-33032

PTL 2: JP-A-2005-264759

SUMMARY OF INVENTION Technical Problem

In the blow-by gas reflux system, the oil contained in the blow-by gas discharged from the internal combustion engine is removed via the oil separator. However, the oil may not be completely removed by the oil separator, so that a small amount of oil may be contained in the blow-by gas after passing through the oil separator. In a case where an operating state of the compressor is a high supercharging operating state (a case where an intake air temperature after supercharging is high, a case where an intake air pressure after supercharging is high, and the like), when the blow-by gas after passing through the oil separator is refluxed to the intake passage and is introduced into the compressor, oil caulking due to the oil contained in the blow-by gas may occur in the compressor.

The present disclosure has been made in view of the above situations, and an object thereof is to provide a blow-by gas reflux system, a blow-by gas reflux system control device and a storage medium capable of suppressing occurrence of oil caulking.

Solution to Problem

In order to achieve the above object, a blow-by gas reflux system according to an illustrative aspect of the present disclosure includes: a blow-by gas reflux path causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator, which is configured to remove oil from the blow-by gas, and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; an atmospheric release mechanism disposed at a position further downstream side of the blow-by gas reflux path than the oil separator, the atmospheric release mechanism being configured to release the blow-by gas after passing through the oil separator into an atmosphere; and a control device, wherein the control device includes: a determination unit configured to determine whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through the oil separator; and a control unit configured to: in a case the determination unit determines that the oil caulking does not occur, stop the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism; and in a case the determination unit determines that the oil caulking occurs, control the atmospheric release mechanism to release the blow-by gas into the atmosphere.

Further, in order to achieve the above object, a control device of a blow-by gas reflux system of an illustrative aspect of the present disclosure is a control device applied to a blow-by gas reflux system, the blow-by gas reflux system including: a blow-by gas reflux path for causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator, which is configured to remove oil from the blow-by gas, and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; and an atmospheric release mechanism disposed at a further downstream-side part of the blow-by gas reflux path than the oil separator and configured to release the blow-by gas after passing through the oil separator into an atmosphere, the control device includes: a determination unit configured to determine whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through the oil separator; and a control unit configured to: in a case the determination unit determines that the oil caulking does not occur, stop the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism; and in a case the determination unit determines that the oil caulking occurs, control the atmospheric release mechanism to release the blow-by gas into the atmosphere.

Further, a computer-readable storage medium of an illustrative aspect of the present disclosure is a computer-readable medium storing a computer program readable by a computer of a vehicle, the vehicle including a blow-by gas reflux system including a blow-by gas reflux path for causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator configured to remove oil from the blow-by gas and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; and an atmospheric release mechanism disposed at a further downstream-side part of the blow-by gas reflux path than the oil separator and configured to release the blow-by gas after passing through the oil separator into an atmosphere, and wherein the computer program, when executed by the computer, causes the vehicle to perform: determining whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through the oil separator; stopping the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism, when it is determined that the oil caulking does not occur; and causing the atmospheric release mechanism to release the blow-by gas into the atmosphere, when it is determined that the oil caulking occurs.

Advantageous Effects of Invention

According to the present disclosure, it is possible to suppress occurrence of oil caulking.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a pictorial configuration view of an internal combustion engine system to which a blow-by gas reflux system in accordance with a first embodiment and a second embodiment is applied, depicting a state where a blow-by gas is refluxed to an intake passage.

FIG. 2 is a pictorial configuration view of the internal combustion engine system to which the blow-by gas reflux system in accordance with the first embodiment and the second embodiment is applied, depicting a state where the blow-by gas is released into an atmosphere.

FIG. 3 is a flowchart depicting an example of control processing of an atmospheric release mechanism that is performed by a control device in accordance with the first embodiment.

FIG. 4 is a flowchart depicting an example of control processing of the atmospheric release mechanism that is performed by the control device in accordance with the second embodiment.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinbelow, a blow-by gas reflux system 60 and a control device 50 of the blow-by gas reflux system 60 in accordance with a first embodiment will be described with reference to the drawings. Specifically, a schematic configuration of an internal combustion engine system 1 to which the blow-by gas reflux system 60 in accordance with the present embodiment is applied is first described, and the blow-by gas reflux system 60 and the control device 50 thereof are then described.

The internal combustion engine system 1 exemplified in FIG. 1 includes an internal combustion engine 10, an intake passage 20, an air cleaner 30, a supercharger 40, a control device 50, and a blow-by gas reflux system 60. In the meantime, the internal combustion engine system 1 in accordance with the present embodiment is mounted on a vehicle. A specific type of the vehicle is not particularly limited, and a variety of vehicles such as a passenger car, a commercial vehicle can be used.

The internal combustion engine 10 has an internal combustion engine main body 11. The internal combustion engine main body 11 has a cylinder block in which cylinders are formed, a cylinder head disposed on an upper part of the cylinder block, a piston disposed in the cylinder, and a crankshaft connected to the piston via a connecting rod. Also, the internal combustion engine 10 has a crankcase 12. The crankcase 12 is connected to a lower part of the cylinder block. The crankshaft is accommodated in the crankcase 12. Also, the internal combustion engine 10 has a cylinder head cover 13. The cylinder head cover 13 is disposed on an upper part of the cylinder head. In the cylinder head cover 13, a valve mechanism such as a cam is accommodated.

A specific type of the internal combustion engine 10 is not particularly limited, and a variety of internal combustion engines such as a Diesel engine, a gasoline engine and the like can be used. In the present embodiment, a Diesel engine is used as an example of the internal combustion engine 10.

The intake passage 20 is a passage through which an intake air (A) sucked in the internal combustion engine 10 passes. A downstream-side end portion of the intake passage 20 connects to an intake port of the internal combustion engine 10. In the meantime, although not shown, the internal combustion engine 10 has also an exhaust passage through which an exhaust air discharged from the internal combustion engine 10 passes. An upstream-side end portion of the exhaust passage connects to an exhaust port of the internal combustion engine 10. The air cleaner 30 is disposed at a further upstream part of the intake passage 20 than the supercharger 40. In the meantime, the intake air that flows into the intake passage 20 from an upstream-side end portion of the intake passage 20 is fresh air. The air cleaner 30 is a member having a function of removing foreign materials such as dirt and dust contained in the fresh air.

The supercharger 40 is a device configured to supercharge the intake air sucked in the internal combustion engine 10 by a compressor 41. A specific configuration of the supercharger 40 is not particularly limited inasmuch as it has such function. For example, a variety of superchargers such as a turbo supercharger where the compressor 41 is driven using energy of the exhaust air, a mechanical supercharger where the compressor 41 is driven by power of the internal combustion engine 10, an electric supercharger where the compressor 41 is driven by power of an electric motor, and the like can be used. In the present embodiment, a turbo supercharger is used as an example of the supercharger 40. Specifically, the supercharger 40 in accordance with the present embodiment includes a turbine (not shown) disposed on the exhaust passage, the compressor 41 disposed on the intake passage 20, and a rotary shaft (not shown) coupling the turbine and the compressor 41. The turbine is driven by receiving the energy of the exhaust air, so that the compressor 41 connected to the turbine via the rotary shaft is driven to supercharge the intake air.

The control device 50 is configured by an electronic control device. Specifically, the control device 50 in accordance with the present embodiment includes a microcomputer having a CPU (Central Processing Unit) 51 configured to execute a variety of control processing and a storage unit 52 configured to store a program, data and the like that are used for operations of the CPU 51. In the meantime, the storage unit 52 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

The control device 50 in accordance with the present embodiment is configured to control operations of the internal combustion engine 10 by controlling a fuel injection timing, a fuel injection amount and the like of the internal combustion engine 10. Also, the control device 50 in accordance with the present embodiment functions as a control device of the blow-by gas reflux system 60. In the meantime, the control device of the blow-by gas reflux system 60 may also be a control device that is provided separately from the control device configured to control the internal combustion engine 10.

The blow-by gas reflux system 60 in accordance with the present embodiment is applied to the internal combustion engine system 1 as described above. Subsequently, a configuration of the blow-by gas reflux system 60 is described. The blow-by gas reflux system 60 includes a blow-by gas reflux path 70, an oil separator 80, an atmospheric release mechanism 90 (an atmospheric release passage 91 and a three-way valve 92), a sensor 100 a, a sensor 100 b and the control device 50 as a part of the constitutional elements.

The blow-by gas reflux path 70 is a flow path for refluxing a blow-by gas (Gb) discharged from the internal combustion engine 10 to a further upstream-side part (in the present embodiment, a further downstream-side part than the air cleaner 30) of the intake passage 20 than the compressor 41 after causing the blow-by gas to pass through the oil separator 80. Specifically, the blow-by gas reflux path 70 in accordance with the present embodiment has an upstream-side end portion connected to a blow-by gas exhaust port provided on an outer wall of a side surface of the cylinder head cover 13 of the internal combustion engine 10, and a downstream-side end portion connected to a part of the intake passage 20 on a further upstream-side than the compressor 41 and on a further downstream-side than the air cleaner 30. The oil separator 80 is disposed on the way of the blow-by gas reflux path 70.

The oil separator 80 has a function of removing oil contained in the blow-by gas introduced into the oil separator 80. A specific configuration of the oil separator 80 is not particularly limited inasmuch as it has such function, and a well-known oil separator (which may also be referred to as an oil mist separator) can be used. For this reason, the descriptions of the detailed structure of the oil separator 80 are omitted.

The blow-by gas generated in the internal combustion engine 10 is leaked from a gap between each cylinder and the piston therein to the crankcase 12, passes through the inside of the cylinder head cover 13, and is then introduced into the blow-by gas reflux path 70. Then, the blow-by gas passes through the oil separator 80 and is then refluxed to a further upstream-side part of the intake passage 20 than the compressor 41. In the meantime, the oil contained in the blow-by gas discharged from the internal combustion engine 10 is removed as it passes through the oil separator 80. However, the oil may not be completely removed by the oil separator 80. In this case, a small amount of oil may be contained in the blow-by gas after passing through the oil separator 80.

The atmospheric release mechanism 90 is disposed at a further downstream-side part of the blow-by gas reflux path 70 than the oil separator 80. The atmospheric release mechanism 90 is configured to release the blow-by gas after passing through the oil separator 80 into the atmosphere, in response to an instruction of the control device 50. A specific configuration of the atmospheric release mechanism 90 is not particularly limited inasmuch as it has such function. However, the atmospheric release mechanism 90 in accordance with the present embodiment has an atmospheric release passage 91 and a three-way valve 92, as an example.

The atmospheric release passage 91 has a downstream-side end portion opening to the atmosphere and an upstream-side end portion connected to a further downstream-side passage part of the blow-by gas reflux path 70 than the oil separator 80. The three-way valve 92 is disposed at the connection place of the atmospheric release passage 91 to the blow-by gas reflux path 70. That is, the atmospheric release passage 91 in accordance with the present embodiment is connected to the blow-by gas reflux path 70 via the three-way valve 92.

The three-way valve 92 has a gas inlet 93, a gas outlet 94 a and a gas outlet 94 b, and the gas inlet 93 and the gas outlet 94 a are provided at a further downstream-side passage part of the blow-by gas reflux path 70 than the oil separator 80. The upstream-side end portion of the atmospheric release passage 91 is connected to the gas outlet 94 b of the three-way valve 92. The gas inlet 93 of the three-way valve 92 is always in an opened state. In the meantime, the three-way valve 92 has such a structure that it is controlled by the control device 50, thereby opening and closing independently each of the gas outlet 94 a and the gas outlet 94 b.

As exemplified in FIG. 1, when the three-way valve 92 opens the gas outlet 94 a and closes the gas outlet 94 b, the blow-by gas after passing through the oil separator 80 is not released into the atmosphere and passes through the blow-by gas reflux path 70 and is then refluxed to the intake passage 20.

In the meantime, as exemplified in FIG. 2, when the three-way valve 92 closes the gas outlet 94 a and opens the gas outlet 94 b, the blow-by gas after passing through the oil separator 80 is released into the atmosphere through the atmospheric release passage 91 (in this case, the blow-by gas is not refluxed to the intake passage 20). In this way, the atmospheric release mechanism 90 in accordance with the present embodiment releases the blow-by gas after passing through the oil separator 80 into the atmosphere.

The three-way valve 92 is an example of a member having a function as a flow path switching mechanism configured to switch a flow destination of the blow-by gas after passing through the oil separator 80 between the atmospheric release passage 91 and the intake passage 20.

The configuration of the flow path switching mechanism is not limited to the three-way valve 92 as described above. As another example of the flow path switching mechanism, the flow path switching mechanism may include a first opening/closing valve disposed on the atmospheric release passage 91 and configured to open/close the atmospheric release passage 91 and a second opening/closing valve disposed on a further downstream-side passage part of the blow-by gas reflux path 70 than the connection place of the atmospheric release passage 91 and configured to open/close the connection place. In this case, the control device 50 can release the blow-by gas after passing through the oil separator 80 into the atmosphere through the atmospheric release passage 91 by controlling the first opening/closing valve to an opened state and the second opening/closing valve to a closed state. On the other hand, the control device 50 can reflux the blow-by gas after passing through the oil separator 80 to the intake passage 20 by controlling the first opening/closing valve to a closed state and the second opening/closing valve to an opened state.

Also, the place of the blow-by gas reflux path 70 on which the three-way valve 92 is disposed may be a further downstream-side part than the oil separator 80 and is not limited to the place exemplified in FIGS. 1 and 2. In the meantime, as the place of the blow-by gas reflux path 70 on which the three-way valve 92 is disposed is closer to the oil separator 80, it is possible to more effectively suppress the blow-by gas from being cooled by the atmosphere until the blow-by gas after passing through the oil separator 80 flows into the three-way valve 92. Therefore, it is preferably to set the disposal place of the three-way valve 92, taking into account this point.

Referring to FIG. 1, the sensor 100 a is configured to detect a temperature (referred to as “intake air temperature T after supercharging”) of the intake air supercharged by the compressor 41 and to transmit a detection result to the control device 50. That is, the sensor 100 a in accordance with the present embodiment is a temperature sensor configured to detect the intake air temperature T after supercharging. Specifically, the sensor 100 a in accordance with the present embodiment is disposed near an intake air outlet of the compressor 41, and is configured to detect a temperature of the intake air immediately after discharged from the compressor 41.

The sensor 100 b is configured to detect a temperature of the atmosphere (referred to as “atmospheric temperature Ta”) and to transmit a detection result to the control device 50. That is, the sensor 100 b in accordance with the present embodiment is a temperature sensor configured to detect the atmospheric temperature Ta. In the meantime, the detection result of the sensor 100 b is not used in control processing (control processing shown in FIG. 3, which will be described later) in accordance with the present embodiment, and the detection result of the sensor 100 b is used in control processing of FIG. 4 (control processing of a second embodiment). For this reason, the blow-by gas reflux system 60 in accordance with the present embodiment may also be configured not to include the sensor 100 b.

Subsequently, control of the atmospheric release mechanism 90 that is performed by the control device 50 is described with reference to a flowchart shown in FIG. 3. In the meantime, each step in FIG. 3 is executed by the CPU 51 of the control device 50, based on a program stored in the storage unit 52. The control device 50 first starts the flowchart of FIG. 3 at the same time when the internal combustion engine 10 starts (i.e., the flowchart of FIG. 3 is periodically executed during the operation of the internal combustion engine 10). Also, it is assumed that upon first start of FIG. 3, the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism 90 is stopped.

In step S10 of FIG. 3, the control device 50 determines whether oil caulking due to the oil contained in the blow-by gas (Gb) after passing through the oil separator 80 occurs in the compressor 41, based on the operating state of the compressor 41. The specific execution content of step S10 is described as follows.

First, the control device 50 in accordance with the present embodiment uses the temperature (i.e., the intake air temperature T after supercharging) of the intake air supercharged by the compressor 41, as a parameter relating to the operating state of the compressor 41. As an operating load of the compressor 41 increases, the intake air temperature T after supercharging intends to increase. That is, the intake air temperature T after supercharging is a parameter having correlation with the operating load of the compressor 41. The control device 50 obtains the detection result of the sensor 100 a to obtain the intake air temperature T after supercharging. The control device 50 determines whether the obtained intake air temperature T after supercharging is equal to or higher than a predetermined threshold value T1, and determines that oil caulking occurs (YES) when it is determined that the intake air temperature T after supercharging is equal to or higher than the threshold value T1.

The threshold value T1 may be any value by which it is possible to determine that oil caulking occurs when the intake air temperature T after supercharging is equal to or higher than the corresponding value. As the threshold value T1, an appropriate value may be obtained in advance by performing a test, a simulation and the like, and may be stored in the storage unit 52 of the control device 50. In this way, step S10 in accordance with the present embodiment is executed.

The execution content of step S10 is not limited to the above. As another example, in step S10, the control device 50 may estimate the intake air temperature T after supercharging, based on a parameter (for example, the operating state of the internal combustion engine 10) having correlation with the intake air temperature T after supercharging, instead of using the detection result of the sensor 100 a. Specifically, in this case, a control map in which the intake air temperature T after supercharging is associated with the number of rotations of the internal combustion engine 10 and the load of the internal combustion engine 10 (for example, a fuel injection amount) is stored in advance in the storage unit 52. The control device 50 may obtain the number of rotations and the load of the internal combustion engine 10, extract the intake air temperature T after supercharging corresponding to the obtained number of rotations and load from the control map, and use the extracted intake air temperature T after supercharging in step S10.

Alternatively, in step S10, the control device 50 may use a pressure (referred to as “supercharging pressure P”) of the intake air supercharged by the compressor 41, as a parameter relating to the operating state of the compressor 41. The supercharging pressure P is also a parameter whose value tends to increase as the operating load of the compressor 41 increases. In the meantime, when the supercharging pressure P is used as a parameter relating to the operating state of the compressor 41, a pressure sensor configured to detect the supercharging pressure P is used as the sensor 100 a. In step S10, the control device 50 determines whether the supercharging pressure P detected by the sensor 100 a as the pressure sensor is equal to or higher than a predetermined threshold value P1, and determines that oil caulking occurs (YES) when it is determined that the supercharging pressure P is equal to or higher than the threshold value P1. Similarly to the threshold value T1, the threshold value P1 may also be any value by which it is possible to determine that oil caulking occurs when the supercharging pressure P is equal to or higher than the corresponding value. As the threshold value P1, an appropriate value may be obtained in advance by performing a test, a simulation and the like, and may be stored in the storage unit 52 of the control device 50.

Also, when obtaining the supercharging pressure P, the control device 50 may estimate the same, based on a parameter (for example, the operating state of the internal combustion engine 10) having correlation with the supercharging pressure P. Specifically, in this case, a control map in which the supercharging pressure P is associated with the number of rotations of the internal combustion engine 10 and the load of the internal combustion engine 10 is stored in advance in the storage unit 52. The control device 50 may obtain the number of rotations and the load of the internal combustion engine 10, extract the supercharging pressure P corresponding to the obtained number of rotations and load from the control map, and use the extracted supercharging pressure P in step S10.

By the diverse methods, step S10 can be executed. When a determination result in step S10 is NO (when it is determined that oil caulking does not occur), the control device 50 executes step S20. In step S20, the control device 50 stops the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism 90 (when the release of the blow-by gas into the atmosphere has been already stopped before execution of step S20, this state is maintained in step S20). Specifically, as described above, the control device 50 controls the gas outlet 94 a of the three-way valve 92 of the atmospheric release mechanism 90 to the opened state and the gas outlet 94 b to the closed state. Thereby, the blow-by gas after passing through the oil separator 80 passes through the blow-by gas reflux path 70 and is then refluxed to the intake passage 20. After executing step S20, the control device 50 again executes the flowchart from the start (return).

On the other hand, when a determination result in step S10 is YES (when it is determined that oil caulking occurs), the control device 50 executes step S30. In step S30, the control device 50 causes the atmospheric release mechanism 90 to release the blow-by gas into the atmosphere. Specifically, as described above, the control device 50 controls the gas outlet 94 a of the three-way valve 92 of the atmospheric release mechanism 90 to the closed state and the gas outlet 94 b to the opened state. Thereby, the blow-by gas after passing through the oil separator 80 passes through the atmospheric release passage 91 and is then released to the atmosphere.

After executing step S30, the control device 50 again executes the flowchart from the start (return). In the meantime, the release of the blow-by gas into the atmosphere in step S30 is continuously executed until when a determination result in step S10 becomes NO during the re-execution of the flowchart. That is, according to the present embodiment, the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism 90 is continuously executed until it is determined that oil caulking does not occur in the compressor 41.

In the present embodiment, the CPU 51 of the control device 50 that executes step S10 is an example of a member having a function as “determination unit”. Also, the CPU 51 of the control device 50 that executes step S20 and step S30 is an example of a member having a function as “control unit”.

According to the present embodiment as described above, when it is determined based on the operating state of the compressor 41 that oil caulking occurs (YES in step S10), the control processing relating to step S30 is executed, so that the blow-by gas after passing through the oil separator 80 can be released into the atmosphere. Thereby, since the blow-by gas containing oil is not introduced into the compressor 41, it is possible to suppress oil caulking from occurring in the compressor 41. Also, according to the present embodiment, since the blow-by gas after passing through the oil separator 80 is released into the atmosphere, the amount of oil in the blow-by gas that is released into the atmosphere is smaller, as compared to a case where the blow-by gas before passing through the oil separator 80 is released into the atmosphere. That is, according to the present embodiment, while suppressing the oil contained in the blow-by gas discharged from the internal combustion engine 10 from being released into the atmosphere in a large amount, it is possible to suppress oil caulking from occurring in the compressor 41.

As a result, according to the present embodiment, while suppressing atmospheric pollution due to the oil released into the atmosphere as much as possible, it is possible to suppress oil caulking from occurring in the compressor 41, thereby suppressing lowering in supercharging efficiency of the compressor 41 due to oil caulking.

Second Embodiment

Subsequently, a blow-by gas reflux system 60 and a control device 50 in accordance with a second embodiment are described. In the meantime, the hardware configuration of the blow-by gas reflux system 60 in accordance with the present embodiment is the same as that of the blow-by gas reflux system 60 in accordance with the first embodiment. The processing that is executed by the control device 50 of the blow-by gas reflux system 60 in accordance with the present embodiment is different from the first embodiment. Specifically, the control device 50 in accordance with the present embodiment is different from the control device 50 in accordance with the first embodiment, in that a flowchart of FIG. 4 is executed instead of the flowchart of FIG. 3.

The flowchart of FIG. 4 is different from the flowchart of FIG. 3, in that it further includes step S15. The control device 50 in accordance with the present embodiment executes step S15 when a determination result in step S10 of FIG. 4 is YES. In step S15, the control device 50 determines whether the atmospheric temperature Ta is equal to or lower than a predetermined threshold value Ta1 (i.e., low temperature). The technical background of executing step S15 and detailed contents of step S15 are described as follows.

First, when step S30 is executed and the blow-by gas after passing through the oil separator 80 is thus released into the atmosphere, the blow-by gas does not pass through the connection place (specifically, the place in which the three-way valve 92 is disposed) of the atmospheric release mechanism 90 on the blow-by gas reflux path 70. As a result, a further downstream-side part of the blow-by gas reflux path 70 than the atmospheric release mechanism 90 is cooled by the atmosphere, so that the temperature thereof is lowered.

Herein, when the atmospheric temperature is low, as the moisture attached to the further downstream-side part of the blow-by gas reflux path 70 than the atmospheric release mechanism 90 is frozen, the blow-by gas reflux path 70 is further cooled. In the cooled state, when the reflux of the blow-by gas to the intake passage 20 is resumed, the moisture contained in the blow-by gas is frozen at the time when the moisture is attached to a pipe wall part of the blow-by gas reflux path 70. As a result, a frozen material (for example, chips of ice) due to the freezing is generated in the blow-by gas reflux path 70. When the frozen material flows downstream together with the blow-by gas and is introduced into the compressor 41, the compressor 41 may malfunction.

Therefore, in the present embodiment, in order to solve the above problem, step S15 is executed. Specifically, the threshold value Ta1 that is used for the determination processing in step S15 is stored in advance (i.e., predetermined) in the storage unit 52 of the control device 50 in accordance with the present embodiment. In the present embodiment, as the threshold value Ta1, an atmospheric temperature at which the freezing occurs in the further downstream-side part of the blow-by gas reflux path 70 than the atmospheric release mechanism 90 is used. That is, in the present embodiment, when the atmospheric temperature Ta is equal to or lower than the threshold value Ta1, as the freezing occurs in the further downstream-side part of the blow-by gas reflux path 70 than the atmospheric release mechanism 90, the atmospheric temperature Ta is lowered. As the threshold value Ta1, an appropriate value may be obtained in advance by performing a test, a simulation and the like, and may be stored in the storage unit 52 of the control device 50.

Then, in step S15, the control device 50 obtains the atmospheric temperature Ta, based on the detection result of the sensor 100 b, and determines whether the obtained atmospheric temperature Ta is equal to or lower than the threshold value Ta1 stored in the storage unit 52. When it is determined that the atmospheric temperature Ta is equal to or lower than the threshold value Ta1, the control device 50 determines YES and executes step S20. When it is determined that the atmospheric temperature Ta is not equal to or lower than the threshold value Ta1, the control device 50 determines NO and executes step S30.

That is, when it is determined that oil caulking occurs (YES in step S10) and it is also determined that the atmospheric temperature Ta is equal to or lower than the threshold value Ta1 (YES in step S15), the control device 50 in accordance with the present embodiment stops the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism 90 and refluxes the blow-by gas to the intake passage 20 (step S20), and when it is determined that oil caulking occurs (YES in step S10) and it is also determined that the atmospheric temperature Ta is not equal to or lower than the threshold value Ta1 (NO in step S15), the control device 50 causes the atmospheric release mechanism 90 to release the blow-by gas into the atmosphere (step S30).

In the present embodiment, the execution sequence of step S10 and step S15 is not limited to the sequence shown in FIG. 4. As another example, the control device 50 may execute step S15 before step S10. In this case, when a determination result in step S15 is NO, step S10 is executed, and when a determination result in step S15 is YES, step S20 is executed.

In the present embodiment, the CPU 51 of the control device 50 that executes step S10 and step S15 is an example of a member having a function as “determination unit”. Also, the CPU 51 of the control device 50 that executes step S20 and step S30 is an example of a member having a function as “control unit”.

According to the present embodiment as described above, it is possible to achieve following effects, in addition to the operational effects of the first embodiment. Specifically, according to the present embodiment, it is possible to suppress the frozen material generated in the further downstream-side part of the blow-by gas reflux path 70 than the atmospheric release mechanism 90 from being introduced into the compressor 41. Thereby, it is possible to suppress the malfunction of the compressor 41, which is caused when the frozen material is introduced. Specifically, it is possible to suppress the malfunction such as a damage of the compressor 41, which is caused when the frozen material is introduced into the compressor 41.

Although the embodiments of the present disclosure have been described, the present disclosure is not limited to the specific embodiments and can be diversely modified/changed within the scope of the present invention.

The subject application is based on Japanese Patent Application No. 2018-078205 filed on Apr. 16, 2018, the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The present invention has the effect of suppressing occurrence of oil caulking, and is useful for the blow-by gas reflux system, the blow-by gas reflux system control device, the storage medium, and the like.

REFERENCE SIGNS LIST

-   1: internal combustion engine system -   10: internal combustion engine -   20: intake passage -   30: air cleaner -   40: supercharger -   41: compressor -   50: control device -   51: CPU (determination unit, control unit) -   52: storage unit -   60: blow-by gas reflux system -   70: blow-by gas reflux path -   80: oil separator -   90: atmospheric release mechanism -   91: atmospheric release passage -   92: three-way valve -   100 a, 100 b: sensor 

1. A blow-by gas reflux system comprising: a blow-by gas reflux path causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator, which is configured to remove oil from the blow-by gas, and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; an atmospheric release mechanism disposed at a position further downstream side of the blow-by gas reflux path than the oil separator, the atmospheric release mechanism being configured to release the blow-by gas after passing through the oil separator into an atmosphere; and a control device; configured to: determine whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through die oil separator; in a case it is determined that the oil caulking does not occur, stop the release of the blow-by gas into the atmosphere performed by die atmospheric release mechanism; and in a case it is determined that the oil caulking occurs, control the atmospheric release mechanism to release the blow-by gas into the atmosphere.
 2. The blow-by gas reflux system according to claim 1, wherein the control device is configured to further determine whether an atmospheric temperature is equal to or lower than a predetermined threshold value, wherein in a case it is determined that the oil caulking occurs and also determined that the atmospheric temperature is equal to or lower than the threshold value, the control device is configured to stop the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism, and wherein in a case it is determined that the oil caulking occurs and also determined that the atmospheric temperature is not equal to or lower titan the threshold value, the control device is configured to control the atmospheric release mechanism to release the blow-by gas into the atmosphere.
 3. A control device applied to a blow-by gas reflux system, the blow-by gas reflux system comprising: a blow-by gas reflux path for causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator, which is configured to remove oil from the blow-by gas, and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; and an atmospheric release mechanism disposed at a further downstream-side part of the blow-by gas reflux path than the oil separator and configured to release the blow-by gas after passing through the oil separator into an atmosphere, the control device being configured to: determine whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through the oil separator; in a case it is determined that the oil caulking does not occur, stop the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism; and in a case it is determined that the oil caulking occurs, control the atmospheric release mechanism to release the blow-by gas into the atmosphere.
 4. A non-transitory computer-readable storage medium storing a computer program readable by a computer of a vehicle, the vehicle comprising a blow-by gas reflux system comprising: a blow-by gas reflux path for causing a blow-by gas discharged from an internal combustion engine to pass through an oil separator configured to remove oil from the blow-by gas and then refluxing the blow-by gas to an intake passage of the internal combustion engine positioned on a further upstream-side than a compressor of a supercharger disposed on the intake passage; and an atmospheric release mechanism disposed at a further downstream-side part of the blow-by gas reflux path than the oil separator and configured to release the blow-by gas after passing through the oil separator into an atmosphere, the computer program, when executed by the computer, causes the vehicle to perform: determining whether oil caulking occurs in the compressor, based on an operating state of the compressor, the oil caulking being caused due to oil contained in the blow-by gas after passing through the oil separator; in a case it is determined that the oil caulking does not occur, stopping the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism; and in a case it is determined that the oil caulking occurs, causing the atmospheric release mechanism to release the blow-by gas into the atmosphere.
 5. The non-transitory computer-readable storage medium according to claim 4, wherein the computer program, when executed by the computer, causes the vehicle to further execute: determining whether an atmospheric temperature is equal to or lower than a predetermined threshold value, when it is determined that the oil caulking occurs; in a case it is determined that the oil caulking occurs and it is also determined that the atmospheric temperature is equal to or lower than the threshold value, stopping the release of the blow-by gas into the atmosphere performed by the atmospheric release mechanism; and in a case it is determined that the oil caulking occurs and it is also determined that the atmospheric temperature is not equal to or lower than the threshold value, causing the atmospheric release mechanism to release the blow-by gas into the atmosphere. 